Anti-reflective film

ABSTRACT

The present disclosure relates to an anti-reflective film comprising: a hard coating layer; and a low refractive index layer, wherein a particle-mixed layer containing both hollow inorganic nanoparticles and solid inorganic nanoparticles and having a thickness of 1.5 nm to 22 nm exists in the low refractive index layer, and wherein the anti-reflective film has a ratio of the reflectance at a wavelength of 400 nm to the reflectance at a wavelength of 550 nm of 1.3 to 2.7, and a polarizing plate, a display device, and an organic light emitting diode display device comprising the anti-reflective film.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a 35 U.S.C. 371 National Phase Entry Applicationfrom PCT/KR2021/003226, filed on Mar. 16, 2021, which claims the benefitof Korean Patent Application Nos. 10-2020-0032251 and 10-2020-0032253filed on Mar. 16, 2020 and Korean Patent Application Nos.10-2021-0033696 and 10-2021-0033702 filed on Mar. 16, 2021 with theKorean Intellectual Property Office, all of the disclosures of which areincorporated herein by reference in their entirety.

The present application relates to an anti-reflective film, a polarizingplate, a display device, and an organic light emitting diode displaydevice.

BACKGROUND OF THE INVENTION

In general, in flat panel display devices such as a PDP, an LCD, etc.,an anti-reflective film is installed so as to minimize reflection ofincident light from the outside.

Methods for minimizing the reflection of light include a method ofdispersing a filler such as fine inorganic particles, etc. in a resin,coating it on a substrate film, and forming unevenness (anti-glare: AGcoating), a method of using light interference by forming multiplelayers having different refractive indexes on a substrate film(anti-reflective; AR coating), a method of using them together, etc.

Among them, in the case of AG coating, although the absolute amount ofreflected light is equivalent to that of common hard coatings, a lowreflection effect can be obtained by reducing the amount of lightentering the eyes using light scattering through unevenness. However,since the AG coating has lowered screen sharpness due to the surfaceunevenness, recently, many studies are being conducted on AR coating.

As films using the AR coating, those having a multi-layered structure inwhich a hard coating layer (high refractive index layer), a lowreflective coating layer, etc. are stacked on a substrate film are beingcommercialized. However, since the method of forming multiple layersconducts individual processes for forming each layer, it has adisadvantage in terms of lowered scratch resistance due to weakinterlayer adhesion (interface adhesion).

Further, previously, in order to improve scratch resistance of the lowrefractive index layer included in the anti-reflective film, a method ofadding various particles of a nanometer size (for example, silica,alumina, zeolite, etc.) was mainly attempted. However, whennanometer-sized particles are used, there is a limitation in that it isdifficult to simultaneously increase scratch resistance while loweringthe reflectance of the low refractive index layer, and due to thenanometer-sized particles, the anti-fouling property of the surface ofthe low refractive index layer is significantly deteriorated.

Accordingly, in order to reduce the absolute reflection amount ofincident light from the outside and improve the anti-fouling property aswell as scratch resistance of the surface, many studies are beingconducted, but the property improvement degree resulting therefrom isunsatisfactory.

BRIEF SUMMARY OF THE INVENTION

The present disclosure provides an anti-reflective film that cansimultaneously realize high scratch resistance and anti-foulingproperties while having high light transmittance, and that has colorlessand transparent properties while realizing low reflectance.

The present disclosure also provides a polarizing plate including theanti-reflective film.

The present disclosure further provides a display device including theanti-reflective film.

The present disclosure further provides an organic light emitting diodedisplay device including the anti-reflective film.

According to one aspect of the present disclosure, there is provided ananti-reflective film comprising: a hard coating layer; and a lowrefractive index layer, wherein a particle-mixed layer containing bothhollow inorganic nanoparticles and solid inorganic nanoparticles andhaving a thickness of 1.5 nm to 22 nm exists in the low refractive indexlayer, and wherein the anti-reflective film has a ratio of thereflectance at a wavelength of 400 nm to the reflectance at a wavelengthof 550 nm of 1.3 to 2.7.

According to another aspect of the present disclosure, there is provideda polarizing plate comprising the above-mentioned anti-reflective filmand a polarizer.

According to yet another aspect of the present disclosure, there isprovided a display device comprising the above-mentioned anti-reflectivefilm.

According to a further aspect of the present disclosure, there isprovided an organic light emitting diode display device comprising theabove-mentioned anti-reflective film.

DETAILED DESCRIPTION OF THE INVENTION

Now, an anti-reflective film, a polarizing plate, a display device, andan organic light emitting diode display device according to specificembodiment of the present disclosure will be described in more detail.

In the present specification, a photopolymerizable compound collectivelyrefers to a compound that causes a polymerization reaction if light, forexample visible rays or ultraviolet rays, is irradiated thereto.

Further, a fluorine-containing compound refers to a compound containingat least one fluorine element in the compound.

Further, the “(meth)acryl” means including both acryl and methacryl.

The “(co)polymer” means including both copolymer and homopolymer.

Additionally, silica hollow particles are silica particles derived froma silicon compound or an organosilicon compound, wherein an empty spaceexists on the surface and/or inside of the silica particles.

Further, the low refractive index layer may refer to a layer having alow refractive index as compared with another layer in theanti-reflective film, for example, a hard coating layer.

For example, the low refractive index layer may have a refractive indexof 1.65 or less, or 1.60 or less, or 1.57 or less, or 1.55 or less, or1.53 or less at a wavelength of 550 nm.

According to one embodiment of the present disclosure, ananti-reflective film is provided, including: a hard coating layer; and alow refractive index layer, wherein a particle-mixed layer containingboth hollow inorganic nanoparticles and solid inorganic nanoparticlesand having a thickness of 1.5 nm to 22 nm exists in the low refractiveindex layer, and wherein the anti-reflective film has a ratio of thereflectance at a wavelength of 400 nm to the reflectance at a wavelengthof 550 nm of 1.3 to 2.7.

When the anti-reflective film including the low refractive index layerand the hard coating layer has a low refractive index, for example, areflectance of 1.5% or less at a wavelength of 550 nm, the reflectancein a blue region is higher than the reflectance in a green region. As aresult, the anti-reflective layer may have a blue color and thus have anopacity or color property to the extent that it is not suitable forapplication to a polarizing plate or a display device.

Thus, the present inventors conducted studies on an anti-reflectivefilm, confirmed through experiments that if a particle-mixed layercontaining both hollow inorganic nanoparticles and solid inorganicnanoparticles and having a predetermined thickness in the low-refractivelayer is included in the anti-reflective film, the bluishness can besignificantly reduced while realizing low reflectance, and the colorlessand transparent properties can be realized, thereby completing thepresent disclosure. In addition, the anti-reflective film can have ahigh light transmittance together with the above-describedcharacteristics, and also can simultaneously high scratch resistance andanti-fouling properties.

As described above, due to the existence of the particle-mixed layer,the anti-reflective film can have colorless and transparent propertieswhile realizing a low reflectance. As the low refractive index layerincludes hollow inorganic nanoparticles and solid inorganicnanoparticles, it is possible to simultaneously realize high scratchresistance and anti-fouling properties while having high lighttransmittance.

Specifically, the anti-reflective film may have a characteristic thatthe ratio of the reflectance at a wavelength of 400 nm to thereflectance at a wavelength of 550 nm is 1.3 to 2.7, or 1.5 to 2.5.

As the anti-reflective film satisfies a characteristic that the ratio ofthe reflectance at a wavelength of 400 nm to the reflectance at awavelength of 550 nm is 1.3 to 2.7, or 1.5 to 2.5, or 1.40 to 2.30, theanti-reflective film can have optical characteristics that thereflectance in a blue region is lower than the reflectance in a greenregion, thereby capable of having colorless and transparent propertieswhile realizing a low reflectance.

When the ratio of the reflectance at a wavelength of 400 nm to thereflectance at a wavelength of 550 nm that the anti-reflective film hasexceeds 2.7, the anti-reflective film may have a blue color, and thusmay have an opacity or color property to the extent that it is notsuitable for application to a polarizing plate or a display device. Inparticular, in the case of an anti-reflective film in which the ratio ofthe reflectance at a wavelength of 400 nm to the reflectance at awavelength of 550 nm exceeds 2.7, the color reproduction capability ofthe organic light emitting diode display device may be deteriorated.

In a range where the anti-reflective film satisfies the ratio of thereflectance at a wavelength of 400 nm to the reflectance at a wavelengthof 550 nm of 1.3 to 2.7, the reflectance of the anti-reflective film ata wavelength of 550 nm may be more than 0.5% and 1.5% or less, or 0.55%to 1.35%, or 0.59 to 1.32%, and the reflectance of the anti-reflectivefilm at a wavelength of 400 nm may be 1.0% to 3.50%, or 1.20% to 2.60%.

On the other hand, the anti-reflective film includes the particle-mixedlayer having a predetermined thickness in the low refractive indexlayer, and thus the ratio of the reflectance at a wavelength of 400 nmto the reflectance at a wavelength of 550 nm that the anti-reflectivefilm has may be 1.3 to 2.7, or 1.5 to 2.5. Thereby, the anti-reflectivefilm can have a characteristic that the absolute value of b* in a CIELab color space is 4 or less, or 3 or less, or 2 or less, or 1.5 orless.

More specifically, the anti-reflective film includes the particle-mixedlayer in the low refractive index layer, and thus the absolute value ofb* in the CIE Lab color space is 4 or less, or 3 or less, or 2 or less,or 1.5 or less.

Each numerical value in the CIE Lab color space can be measured byapplying a general method of measuring each coordinate of the colorspace, and for example, can be measured according to a manufacturer'smanual after positioning an equipment with an integrating sphere typedetector (spectrophotometer) (ex. CM-2600d, KONICA MINOLTA) at ameasuring position. In one example, each coordinate of the CIE Lab colorspace may also be measured under a state where the polarizer orpolarizing plate is attached to a liquid crystal panel, for example, ahighly reflective liquid crystal panel, or may also be measured for thepolarizer or polarizing plate itself.

The CIE Lab color space is a color space in which the CIE XYZ colorspace is nonlinearly transformed based on human visual antagonistictheory. In this color space, the L value represents brightness, where ifthe L* value is 0, it represents black, and if the L* value is 100, itrepresents white. Also, if the a* value is a negative number, the colorbecomes a color slated to green and if it is a positive number, thecolor becomes a color slanted to red or violet. Furthermore, if the b*value is a negative number, the color becomes a color slanted to blueand if the b* value is a positive number, the color becomes a colorslanted to yellow.

That is, as the anti-reflective film has a characteristic that theabsolute value of b* value in the CIE Lab color space is 4 or less, or 3or less, or 2 or less, or 1.5 or less, it can realize low reflectanceand significantly reduce the degree of red or blue color while realizinglow reflectance, thereby having a colorless and transparent property.

More specifically, the reflectance of the anti-reflection film at awavelength of 550 nm may be more than 0.5% and 1.5% or less, or 0.55% to1.35%, or 0.59 to 1.32%, it can have a characteristic that the absolutevalue of the b* value in the CIE Lab color space is 4 or less, 3 orless, or 2 or less, or 1.5 or less, even while realizing such a lowreflectance.

In this manner, as the absolute value of the b* value in the CIE Labcolor space is maintained at a low level while realizing a lowreflectance, the anti-reflective film can be easily applied to a displayhaving a high contrast ratio and brightness, and can realize highperformance with high color reproduction rate.

In order to have the above-mentioned characteristics of theanti-reflective film, a particle-mixed layer containing both hollowinorganic nanoparticles and solid inorganic nanoparticles and having athickness of 1.5 nm to 22 nm, or 2.0 nm to 20 nm, or 2.2 nm to 18.5 nmmay exist in the low refractive index layer.

If the thickness of the particle-mixed layer is too small, cancelinginterference does not sufficiently occur in the anti-reflective layer,and the absolute value of the b* value may exceed 4.

Further, even when the thickness of the particle-mixed layer is toothick, the absolute value of the b* value in the CIE Lab color spacethat the anti-reflective film has may exceed 4, and thus the opticalproperties such as transparency of the anti-reflective film may bedeteriorated.

Meanwhile, as described above, the particle-mixed layer includes bothhollow inorganic nanoparticles and solid inorganic nanoparticles, andthe volume ratio or distribution aspects thereof is not particularlylimited.

The refractive index or thickness of the particle-mixed layer can beconfirmed through various optical measurement methods, and for example,it can also be confirmed by using a method of fitting a polarizationellipticity measured by an ellipsometry method to a diffusion layermodel.

The polarization ellipticity and related ellipsometry data (ψ, λ)measured by the ellipsometry method can be measured using commonly knownmethods and apparatuses. For example, ellipsometry measurements can beperformed for the particle-mixed layer or other regions included in thelow refractive index layer at an incident angle of 70° in a wavelengthrange of 380 nm to 1000 nm using a J. A. Woollam Co. M-2000 apparatus.

The measured ellipsometry data (ψ, λ) can be fitted to a diffuse layermodel for the mixed layer and to a Cauchy model of Equation 1 for thelower layer and upper layer of the mixed-layer using Complete EASEsoftware, so that MSE becomes 5 or less.

For the particle-mixed layer including both the hollow inorganicnanoparticles and the solid inorganic nanoparticles, the thickness andthe like may not be defined by fitting the measured ellipsometry data tothe Cauchy model of Equation 1.

When the range of the thickness and refractive index of theparticle-mixed layer included in the low refractive index layersatisfies the above range, it can alleviate the abrupt difference inrefractive index between each layer, whereby the anti-reflective filmcan maintain the absolute value of the b* value in the CIE Lab colorspace at a low level while realizing a low reflectance.

Meanwhile, by adjusting the composition of the binder resin included inthe low refractive index layer, the type or content of particles, thespecific process (for example, coating speed, coating method or dryingconditions, etc.) in forming the low refractive index layer, thecharacteristics of the hard coating layer, and the like, it is possibleto form a particle-mixed layer in the low refractive index layer.

Such an example is merely an example of a method or means for formingthe particle-mixed layer, and even if the above methods and means are tobe used simultaneously, the particle-mixed layer is not formed in thelow refractive index layer. These can be adjusted according to thedetailed materials for forming the low refractive index layer and thecontent thereof, the thickness of the low refractive index layer, thedetailed materials of the hard coating layer and the content thereof,the surface characteristics and thickness of the hard coating layer, andthe like. That is, the existence of the particle-mixed layer in the lowrefractive index layer and the effect resulting therefrom can berealized based on the description or examples of the specification.

For example, the hard coating layer contained in the anti-reflectivefilm can include a binder resin including a photocurable resin andorganic or inorganic fine particles dispersed in the binder resin. Whena low refractive index layer including a binder resin, hollow inorganicnanoparticles and solid inorganic nanoparticles is formed on the hardcoating layer through predetermined conditions, the particle-mixed layermay exist.

Further, the hard coating layer included in the anti-reflective film mayhave a surface energy of more than 34 mN/m, or more than 34 mN/m and 60mN/m or less, 34.2 mN/m or more and 59 mN/m or less, or 34.5 mN/m ormore and 58 mN/m or less, or between 35 mN/m and 55 mN/m. When a lowrefractive index layer including a binder resin, hollow inorganicnanoparticles and solid inorganic nanoparticles is formed on the hardcoating layer having a surface energy in such numerical range, theabove-mentioned mixed-particle layer may be formed in the process offitting the surface energy in the low refractive index layer due to thehigh surface energy of the interface.

The surface energy of the hard coating layer can be obtained byadjusting the surface properties of the hard coating layer. For example,the surface energy of the hard coating layer can be controlled byadjusting the surface curing degree, drying conditions, and the like ofthe hard coating layer.

Specifically, the curing degree of the hard coating layer can becontrolled by adjusting curing conditions such as a light irradiationamount or intensity or a flow rate of injected nitrogen in the processof forming the hard coating layer. For example, the hard coating layercan be obtained by subjecting the resin composition for forming the hardcoating layer to ultraviolet irradiation at a dose of 5 to 100 mJ/cm³,or 10 to 25 mJ/cm³ under nitrogen purging in order to apply the nitrogenatmosphere condition.

The above-mentioned surface energy can be measured by determining acontact angle of di water (Gebhardt) and diiodomethane (Owens) at 10points using a commonly known measuring device, for example, a contactangle measuring apparatus DSA-100 (Kruss), calculating an average value,and then converting the average contact angle into the surface energy.Specifically, in the measurement of the surface energy, the contactangle can be converted into the surface energy by using DropshapeAnalysis software and applying the following Equation 2 of the OWRK(Owen, Wendt, Rable, Kaelble) method to the program.

γ_(L)(1+cos θ)=2√{square root over (γ_(S) ^(D)γ_(L) ^(D))}+2√{squareroot over (γ_(S) ^(P)γ_(L) ^(P))}  [Equation 2]

Further, as will be described later, the particle-mixed layer can beformed by applying a drying temperature, an air volume control and thelike at the time of forming the low refractive index layer.

Specifically, the air volume can be adjusted in the drying process byadjusting the drying conditions, for example, the intake or exhaustamount in the process of forming the low refractive index layer. Forexample, in the drying process after coating of the low refractive indexlayer, the air volume may be 0.5 m/s or more, or 0.5 m/s to 10 m/s, or0.5 m/s to 8 m/s, or 0.5 m/s to 5 m/s.

More specifically, the low refractive index layer can be formed on onesurface of the hard coating layer, and the particle-mixed layer may belocated at a distance of 12 nm or more, or 15 nm to 60 nm, or 16 nm to50 nm from one surface of the hard coating layer.

The distance between the particle-mixed layer and one surface of thehard coating layer is not particularly limited, but as theparticle-mixed layer is located at a distance of 12 nm or more from onesurface of the hard coating layer, it plays a role of alleviating theabrupt difference in refractive index between the layers in the lowrefractive index layer, and the absolute value of the slope of thereflectance pattern at a short wavelength is lowered.

When the particle-mixed layer is located in a region of less than 12 nmfrom one surface of the hard coating layer, the effect of alleviatingthe difference in refractive index between layers in the low refractiveindex layer is limited, and the absolute value of the slope of thereflectance pattern cannot be sufficiently obtained.

The distance between the particle-mixed layer and the hard coating layermay be determined as the shortest distance among the distances betweenone surface of the hard coating layer and the particle-mixed layer onthe basis of the plane direction of the hard coating layer.Alternatively, the distance between the particle-mixed layer and thehard coating layer can be defined as a thickness of a region between onesurface of the hard coating layer and the particle-mixed layer.

The existence of the region between one surface of the hard coatinglayer and the particle-mixed layer can be confirmed by the ellipsometrymethod.

Each of the particle-mixed layer and the region between the one surfaceof the hard coat layer and the particle-mixed layer may have specificCauchy parameters A, B, and C when polarization ellipticity measured byellipsometry is fitted to a Cauchy model of Equation 1, and thus theparticle-mixed layer and the region between the one surface of the hardcoating layer and the particle-mixed layer may be distinguished fromeach other.

Specifically, ellipsometry measurements can be performed for the lowrefractive index layer at an incident angle of 70° in a wavelength rangeof 380 nm to 1000 nm using a J. A. Woollam Co. M-2000 apparatus. Themeasured ellipsometry data (ψ, λ) can be fitted to a Cauchy model of thefollowing Equation 1 for low refractive index layer or the detailedlayers of the low refractive index layer using Complete EASE software.

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}1} \right\rbrack\end{matrix}$

in Equation 1, n(λ) is a refractive index at a wavelength λ, λ is arange of 300 nm to 1800 nm, and A, B, and C are Cauchy parameters.

Further, the thickness of each of the particle-mixed layer or the regionbetween one surface of the hard coating layer and the particle-mixedlayer may also be derived through the fitting of the polarizationellipticity measured by the ellipsometry method to a Cauchy model of theEquation 1 and a Diffuse Layer Model. Therefore, each of theparticle-mixed layer or the region between one surface of the hardcoating layer and the particle-mixed layer can be defined in the lowrefractive index layer.

More specifically, the low refractive index layer is formed on onesurface of the hard coating layer, and the low refractive index layermay include hollow inorganic nanoparticles and solid inorganicnanoparticles dispersed in a binder resin, wherein in the low refractiveindex layer, 50% by volume or more, or 60% by volume or more, or 70% byvolume or more, or the numerical value or more or 95% by volume or lessof the whole solid inorganic nanoparticles may exist between one surfaceof the hard coating layer and the particle-mixed layer.

In this manner, as the solid inorganic nanoparticles are mainlydistributed in the region between one surface of the hard coating layerand the particle mixture layer, the region between the one surface ofthe hard coating layer and the mixed particle layer may have arefractive index of 1.46 to 1.65 at a wavelength of 550 nm.

“50% by volume or more of the whole solid inorganic nanoparticles existin a specific region” is defined in the sense that the solid inorganicnanoparticles mainly exists in the specific region in the cross sectionof the low refractive index layer. Specifically, 70% by volume or moreof the whole solid inorganic nanoparticles can be confirmed by measuringthe volume of the whole solid inorganic nanoparticles.

For example, it is possible to visually confirm that each of theregions, in which the solid inorganic nanoparticles and the hollowinorganic nanoparticles each are mainly distributed, exists in the lowrefractive index layer. For example, it is possible to visually confirmthat an individual layer or each region exists in the low refractiveindex layer, using a transmission electron microscope, a scanningelectron microscope, and the like. In addition, the ratio of the solidinorganic nanoparticles and the hollow inorganic nanoparticlesdistributed in the corresponding layer or each of the correspondingregions in the low refractive index layer can also be confirmed.

Further, in the low refractive index layer, 50% by volume or more, or60% by volume or more, or 70% by volume or more, or the numerical valueor more or 95% by volume or less of the whole hollow inorganicnanoparticles may exist in the region from the particle-mixed layer toone surface of the low refractive index layer facing the hard coatinglayer. One surface of the low refractive index layer facing the hardcoating layer means the other surface located in the direction oppositeto the surface in contact with the hard coating layer.

In this manner, as the hollow inorganic nanoparticles are mainlydistributed in the region from the particle-mixed layer to one surfaceof the low refractive index layer facing the hard coating layer, theregion from the particle-mixed layer to one surface of the lowrefractive index layer facing the hard coating layer may have arefractive index of 1.0 to 1.40 at a wavelength of 550 nm.

The above-mentioned particle-mixed layer exists in the low-refractivelayer of the anti-reflective film, the solid inorganic nanoparticles aremainly distributed near the interface between the hard coating layer andthe low-refractive index layer, and the hollow inorganic nanoparticlesare mainly distributed on the opposite side of the interface. It ispossible to form an independent layer in which a region in which each ofthe solid inorganic nanoparticles and the hollow inorganic nanoparticlesare mainly distributed is visually confirmed in the low refractive indexlayer.

Specifically, in the low refractive index layer of the anti-reflectivefilm, when the solid inorganic nanoparticles are mainly distributed nearthe interface between the hard coating layer and the low refractiveindex layer, and the hollow inorganic nanoparticles are mainlydistributed on the opposite side of the interface, lower reflectance canbe achieved compared to the actual reflectance previously obtained usinginorganic particles, and significantly improved scratch resistance andanti-fouling properties can be realized together.

Further, in the anti-reflective film of the embodiment, the region inwhich the solid inorganic nanoparticles and the hollow inorganicnanoparticles are unevenly distributed in the low refractive index layeris divided on the basis of the particle-mixed layer. Accordingly, theanti-reflective film has a reflectance of more than 0.5% and 1.5% orless at a wavelength of 550 nm and an absolute value of b* value of 4 orless, or 3 or less, or 2 or less, or 1.5 or less in the CIE Lab colorspace. Thereby, it is possible to significantly reduce the bluishnesswhile achieving low reflectance, and to have colorless and transparentproperties.

Further, each of the region between the one surface of the hard coatinglayer and the particle-mixed layer and the region from theparticle-mixed layer to the one surface of the low refractive indexlayer facing the hard coating layer can be divided into individuallayers, and as described above, the ratio of the solid inorganicnanoparticles and the hollow inorganic nanoparticles distributed inthese individual layers can also be distinguished.

More specifically, for the region between the one surface of the hardcoating layer and the particle-mixed layer, when the polarizationellipticity measured by an ellipsometry method was fitted to a Cauchymodel of Equation 1 below, it can satisfy the condition that A is 1.00to 1.65, B is 0.0010 to 0.0350, and C is 0 to 1*10⁻³.

Further, the region between one surface of the hard coating layer andthe particle-mixed layer can satisfy the condition that A is 1.25 to1.55, 1.30 to 1.53, or 1.40 to 1.52, B is 0.0010 to 0.0150, 0.0010 to0.0080, or 0.0010 to 0.0050, and C is 0 to 8.0*10⁻⁴, 0 to 5.0*10⁻⁴, or 0to 4.1352*10⁻⁴.

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}1} \right\rbrack\end{matrix}$

in Equation 1, n(λ) is a refractive index at a wavelength λ, λ is arange of 300 nm to 1800 nm, and A, B, and C are Cauchy parameters.

Further, for the region from the particle-mixed layer to one surface ofthe low refractive index layer facing the hard coating layer, when thepolarization ellipticity measured by an ellipsometry method was fittedto the Cauchy model of Equation 1, it can satisfy the condition that Ais 1.00 to 1.50, B is 0 to 0.007, and C is 0 to 1*10⁻³.

Further, the region from the particle-mixed layer to one surface of theoptical function layer facing the polymer resin layer can satisfy thecondition that A is 1.00 to 1.40, 1.00 to 1.39, 1.00 to 1.38, or 1.00 to1.37, B is 0 to 0.0060, 0 to 0.0055, or 0 to 0.00513, and C is 0 to8*10⁻⁴, 0 to 5.0*10⁻⁴, or 0 to 4.8685*10⁻⁴.

On the other hand, each of the particle-mixed layer, the region betweenone surface of the hard coating layer and the particle-mixed layer, andthe region from the particle-mixed layer to one surface of the lowrefractive index layer facing the hard coating layer may share a commonoptical characteristic within one layer, and thus may be defined as alayer.

More specifically, each of the particle-mixed layer, the region betweenone surface of the hard coating layer and the particle-mixed layer, andthe region from the particle-mixed layer to one surface of the lowrefractive index layer facing the hard coating layer has specific Cauchyparameters A, B and C, when the polarization ellipticity measured by theellipsometry method was fitted to the Cauchy model of Equation 1, sothat the first layer and the second layer can be distinguished from eachother. In addition, since the thickness of each layer can also bederived through fitting the polarization ellipticity measured by theellipsometry to the Cauchy model of the Equation 1, it becomes possibleto define each layer within the low refractive index layer.

Meanwhile, the Cauchy parameters A, B, and C derived through the fittingof the polarization ellipticity measured by ellipsometry to a Cauchymodel of Equation 1 may be average values in one region. Thus, if aninterface exists between the respective layers, a region in which theCauchy parameters A, B, and C of the respective layers are overlappedmay exist. However, even in this case, the thicknesses and positions ofthe regions satisfying the average values of the Cauchy parameters A, B,and C of each of the layers may be specified.

Meanwhile, whether the hollow inorganic nanoparticles and solidinorganic nanoparticles exist in the specified region is determined bywhether respective hollow inorganic nanoparticles or solid inorganicnanoparticles exist in the specified region, and is determined byexcluding the particles existing over the boundary surface of thespecific region.

The specific distribution of the solid inorganic nanoparticles and thehollow inorganic nanoparticles in the low refractive index layer is aspecific manufacturing method to be described later can be obtained by aspecific preparation method described later, for example, a method suchas adjusting the density difference between the solid inorganicnanoparticles and the hollow inorganic nanoparticles and adjusting thedrying temperature of the photocurable resin composition for forming alow refractive index layer including the two kinds of nanoparticles, theabove-mentioned method for forming the particle-mixed layer, and thelike.

Specifically, the solid inorganic nanoparticles may have a density whichis 0.50 g/cm³ or more higher than that of the hollow inorganicnanoparticles, and the difference in density between the solid inorganicnanoparticles and the hollow inorganic nanoparticles is 0.50 g/cm³ to3.00 g/cm³, or 0.50 g/cm³ to 2.50 g/cm³, or 0.50 g/cm³ to 2.00 g/cm³, or0.60 g/cm³ to 2.00 g/cm³.

Due to such a difference in density, in the low refractive index layerformed on the hard coating layer, the solid inorganic nanoparticles maybe located on the side closer to the hard coating layer.

However, when the difference in density between the solid inorganicnanoparticles and the hollow inorganic nanoparticles is too large, thesolid inorganic particles may be concentrated at the interface betweenthe low refractive index layer and the hard coating layer, or themovement and uneven distribution of the particles may not be smooth inthe process of forming the low refractive index layer, and a stain mayoccur on the surface of the low refractive index layer or the haze ofthe low refractive index layer may increase significantly, therebyreducing transparency.

Specific types of the solid inorganic nanoparticles include zirconia,titania, antimony pentoxide, silica or tin oxide.

Further, specific types of the hollow inorganic nanoparticles includehollow silica, and the like.

Meanwhile, the low refractive index layer may include a binder resin,and hollow inorganic nanoparticles and solid inorganic nanoparticlesdispersed in the binder resin.

The photopolymerizable compound contained in the photocurable coatingcomposition of the above embodiment may form a base material of thebinder resin of the low refractive index layer prepared.

Specifically, the photopolymerizable compound may include monomers oroligomers including (meth)acrylate or vinyl groups. More specifically,the photopolymerizable compound may include monomers or oligomersincluding one or more, two or more, or three or more (meth)acrylate orvinyl groups.

Specific examples of the monomers or oligomers including a(meth)acrylate may include pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, dipentaerythritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate,tripentaerythritol hepta(meth)acrylate, tolylene diisocyanate, xylenediisocyanate, hexamethylene diisocyanate, trimethylolpropanetri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate,trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate,butanediol dimethacrylate, hexaethyl methacrylate, butyl methacrylate,or a mixture of two or more thereof, or a urethane-modified acrylateoligomer, an epoxide acrylate oligomer, an ether acrylate oligomer, adendritic acrylate oligomer, or a mixture of two or more thereof.Herein, the molecular weight of the oligomers is preferably 1000 to10,000.

Specific examples of the monomer or oligomer containing a vinyl groupinclude divinylbenzene, styrene, and para-methyl styrene.

The content of the photopolymerizable compound in the photocurablecoating composition is not particularly limited, but in consideration ofthe mechanical properties of the finally produced low refractive indexlayer or anti-reflective film, the content of the photopolymerizablecompound in the solid content of the photocurable coating compositioncan be 5% by weight to 80% by weight. The solid content of thephotocurable coating composition means only a liquid component in thephotocurable coating composition, for example, a solid componentexcluding components such as organic solvents that can be optionallyincluded as described below.

The solid inorganic nanoparticles mean particles having a maximumdiameter of 100 nm or less, and having a form in which empty voids arenot present therein.

Further, the hollow inorganic nanoparticles mean particles having amaximum diameter of 200 nm or less and having a form in which emptyvoids are present on the surface and/or inside thereof.

The solid inorganic nanoparticles may have a diameter of 0.5 to 100 nm,or 1 to 50 nm, or 5 to 30 nm, or 10 to 20 nm.

The hollow inorganic nanoparticles may have a diameter of 1 to 200 nm,or 10 to 100 nm, or 50 to 120 nm, or 30 to 90 nm, or 40 to 80 nm.

The diameter of the hollow inorganic nanoparticles and the diameter ofthe solid inorganic nanoparticles may be different.

Further, the diameter of the hollow inorganic nanoparticles may belarger than the diameter of the solid inorganic nanoparticles.

The diameter of each of the solid inorganic nanoparticles and the hollowinorganic nanoparticles may mean the longest diameter of thenanoparticles confirmed in the cross section.

Meanwhile, each of the solid inorganic nanoparticles and the hollowinorganic nanoparticles may have at least one reactive functional groupselected from the group consisting of a (meth)acrylate group, an epoxidegroup, a vinyl group, and a thiol group on the surface thereof. As eachof the solid inorganic nanoparticles and the hollow inorganicnanoparticles contains the above-described reactive functional group onthe surface, the low refractive index layer can have a higher degree ofcrosslinking, thereby securing more improved scratch resistance andanti-fouling property.

The low refractive index layer can be obtained by coating thephotocurable coating composition onto a predetermined substrate andphotocuring the coated product. The specific kind and thickness of thesubstrate are not particularly limited, and a substrate known to beusable in the production of a low refractive index layer or ananti-reflective film can be used without particular limitation.

The method and apparatus commonly used for coating the photocurablecoating composition can be used without particular limitation. Forexample, a bar coating method, such as using a Meyer bar or the like, agravure coating method, a 2-roll reverse coating method, a vacuum slotdie coating method, a 2-roll coating method, or the like can be used.

The low refractive index layer may have a thickness of 20 nm to 240 nm,or 50 nm to 200 nm, or 80 nm to 180 nm.

In the step of photocuring the photocurable coating composition,ultraviolet light or visible light having a wavelength of 200 nm to 400nm can be irradiated, and the amount of exposure during irradiation ispreferably 100 to 4,000 mJ/cm³. The exposure time is not particularlylimited, and can be appropriately varied depending on the exposureapparatus used, the wavelength of the irradiated light, or the amount oflight exposure.

Further, in the step of photocuring the photocurable coatingcomposition, nitrogen purging or the like may be performed to apply anitrogen atmosphere condition.

Meanwhile, the binder resin included in the low refractive index layermay include a crosslinked (co)polymer between a (co)polymer of aphotopolymerizable compound and a fluorine-containing compound includinga photoreactive functional group.

The above-mentioned low refractive index layer can be prepared from aphotocurable coating composition including a photopolymerizablecompound, a fluorine-containing compound including a photoreactivefunctional group, hollow inorganic nanoparticles, solid inorganicnanoparticles, and a photoinitiator. Therefore, the binder resinincluded in the low refractive index layer may include a crosslinked(co)polymer between the (co)polymer of the photopolymerizable compoundand the fluorine-containing compound including the photoreactivefunctional group.

The hydrophobicity of the binder resin including the fluorine-containingcompound and the hydrophilicity of the hard coating layer due to thehigh surface energy may affect the speed at which thefluorine-containing compound moves to the surface of the coating layerduring the drying process of the anti-reflective film. As a result,convection is formed in the solvent, and the fine particles evenlydistributed in the solvent may exhibit different behaviors depending onthe characteristics of the particles. In particular, in this process,each particle can form a plurality of different layers, and when theevaporation of the solvent is finished during the formation of eachlayer, the above-mentioned particle-mixed layer may be formed.

The rise of the surface of the fluorine-containing compound can inducethe rise of the surface of the hollow inorganic nanoparticles, and solidinorganic nanoparticles having a relatively small size are less affectedand phase separation of each particle may occur. During the process,evaporation of the solvent is completed and the fluidity of theparticles disappears, and the above-mentioned mixed layer can be formedby having a predetermined thickness in the low refractive index layer.

The photopolymerizable compound may further include a fluorine-based(meth)acrylate-based monomer or oligomer in addition to theabove-described monomers or oligomers. When the fluorine-based (meth)acrylate-based monomer or oligomer is further included, the weight ratioof the fluorine-based (meth)acrylate-based monomer or oligomer to the(meth)acrylate or vinyl group-containing monomer or oligomer may be 0.1%to 10%.

Specific examples of the fluorine-based (meth)acrylate-based monomer oroligomer include at least one compound selected from the groupconsisting of the following Chemical Formulas 11 to 15.

in Chemical Formula 11, R¹ is a hydrogen group or an alkyl group having1 to 6 carbon atoms, a is an integer of 0 to 7, and b is an integer of 1to 3.

in Chemical Formula 12, c is an integer of 1 to 10.

in Chemical Formula 13, d is an integer of 1 to 11.

in Chemical Formula 14, e is an integer of 1 to 5.

in Chemical Formula 15, f is an integer of 4 to 10.

Meanwhile, the low refractive index layer may further include a portionderived from a fluorine-based compound containing a photoreactivefunctional group.

One or more photoreactive functional groups may be contained orsubstituted in the fluorine-based compound including a photoreactivefunctional group, wherein the photoreactive functional group means afunctional group capable of participating in the polymerization reactionby irradiation with light, for example, by irradiation with visiblelight or ultraviolet light. The photoreactive functional group mayinclude various functional groups known to be capable of participatingin the polymerization reaction by irradiation with light, and specificexamples thereof include a (meth)acrylate group, an epoxide group, avinyl group or a thiol group.

The fluorine-based compound containing a photoreactive functional groupmay have a weight average molecular weight (weight average molecularweight in terms of polystyrene measured by GPC method) of 2,000 to200,000, preferably 5,000 to 100,000.

If the weight average molecular weight of the fluorine-containingcompound including photoreactive functional groups is too small, thefluorine-containing compound may not be uniformly and effectivelyarranged on the surface of the photocurable coating composition and maybe positioned inside of the finally prepared low refractive index layer,and thus the anti-fouling property of the low refractive index layer maybe deteriorated and the crosslinking density of the low refractive indexlayer may be lowered, thus deteriorating mechanical properties such astotal strength, scratch resistance, etc.

Further, if the weight average molecular weight of thefluorine-containing compounds including photoreactive functional groupsis too high, compatibility with other components in the photocurablecoating composition may be lowered, and thus haze of the finallyprepared low refractive index layer may increase or light transmittancemay decrease, and the strength of the low refractive layer may also bedeteriorated.

Specifically, the fluorine-containing compound including a photoreactivefunctional group may include one or more selected from the groupconsisting of: i) aliphatic compounds or alicyclic compounds substitutedby one or more photoreactive functional groups, in which at least onecarbon is substituted by one or more fluorine atoms; ii) heteroaliphaticcompounds or heteroalicyclic compounds substituted by one or morephotoreactive functional groups, in which at least one hydrogen issubstituted by fluorine, and at least one carbon is substituted bysilicon; iii) a polydialkyl siloxane-based polymer (for example, apolydimethyl siloxane-based polymer) substituted by one or morephotoreactive functional groups, in which at least one silicon atom issubstituted by one or more fluorine atoms; iv) polyether compoundssubstituted by one or more photoreactive functional groups, in which atleast one hydrogen is substituted by fluorine, and mixtures orcopolymers of two or more of i) to iv).

The photocurable coating composition may include 20 to 300 parts byweight of the fluorine-containing compound including a photoreactivefunctional group, based on 100 parts by weight of the photopolymerizablecompound.

If the fluorine-containing compound including a photoreactive functionalgroup is excessively added compared to the photopolymerizable compound,the coatability of the photocurable coating composition of the aboveembodiment may be deteriorated or the low refractive index layerobtained from the photocurable coating composition may not havesufficient durability or scratch resistance. Further, if the content ofthe fluorine-containing compound including a photoreactive functionalgroup is too small compared to the photopolymerizable compound, the lowrefractive index layer obtained from the photocurable coatingcomposition may not have sufficient mechanical properties such asanti-fouling property, scratch resistance, etc.

The fluorine-containing compound including a photoreactive functionalgroup may further include silicon or a silicon-containing compound. Thatis, the fluorine-containing compound including a photoreactivefunctional group may optionally contain silicon or a silicon-containingcompound therein, and specifically, the content of silicon in thefluorine-containing compound including a photoreactive functional groupmay be 0.1% by weight to 20% by weight.

The silicon included in the fluorine-containing compound including aphotoreactive functional group may increase compatibility with othercomponents included in the photocurable coating composition, and thusmay prevent the generation of haze in the finally prepared lowrefractive index layer, thereby performing the role of increasingtransparency. Meanwhile, if the content of silicon in thefluorine-containing compound including a photoreactive functional groupbecomes too high, compatibility between the fluorine-containing compoundand other components included in the photocurable coating compositionmay be rather deteriorated, and thus the finally prepared low refractiveindex layer or anti-reflective film may not have sufficient lighttransmittance or anti-reflective performance and the anti-foulingproperty of the surface may also be deteriorated.

The low refractive index layer may include 10 to 500 parts by weight, or50 to 480 parts by weight, or 200 to 400 parts by weight of the hollowinorganic nanoparticles, based on 100 parts by weight of the (co)polymerof photopolymerizable compounds.

The low refractive index layer may include 10 to 400 parts by weight, or50 to 380 parts by weight, or 80 to 300 parts by weight, or 100 to 250parts by weight of the solid inorganic nanoparticles, based on 100 partsby weight of the (co)polymer of photopolymerizable compounds.

The low refractive index layer may include the hollow inorganicnanoparticles and the solid inorganic nanoparticles in relatively highcontents, respectively, relative the low refractive index layer includedin the known optical film.

If the content of the hollow inorganic nanoparticles and solid inorganicnanoparticles in the low refractive index layer becomes excessive, inthe preparation process of the low refractive index layer, phaseseparation between the hollow inorganic nanoparticles and the solidinorganic nanoparticles may not sufficiently occur and they may unevenlydistribute, and thus reflectance may increase, and surface unevennessmay be excessively generated to deteriorate the anti-fouling property.

Further, if the content of the hollow inorganic nanoparticles and solidinorganic nanoparticles in the low refractive index layer is too small,it may be difficult for the majority of the solid inorganicnanoparticles to be positioned near the interface between the hardcoating layer and the low refractive layer, and the reflectance of thelow refractive layer may significantly increase.

The hollow inorganic nanoparticles and the solid inorganic nanoparticlesmay be respectively included in the composition as a colloidal phasedispersed in a predetermined dispersion medium. Each colloidal phaseincluding the hollow inorganic nanoparticles and the solid inorganicnanoparticles may include an organic solvent as a dispersion medium.

Each content of the hollow inorganic nanoparticles and the solidinorganic nanoparticles in a colloidal phase may be determinedconsidering each content range of the hollow inorganic nanoparticles andthe solid inorganic nanoparticles in the photocurable coatingcomposition or the viscosity of the photocurable coating composition,etc., and for example, each solid content of the hollow inorganicnanoparticles and the solid inorganic nanoparticles in the colloidalphase may be 5% by weight to 60% by weight.

Here, the organic solvent in the dispersion medium may include alcoholssuch as methanol, isopropyl alcohol, ethylene glycol, butanol, etc.;ketones such as methyl ethyl ketone, methyl isobutyl ketone, etc.;aromatic hydrocarbons such as toluene, xylene, etc.; amides such asdimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.; esterssuch as ethyl acetate, butyl acetate, gamma butyrolactone, etc.; etherssuch as tetrahydrofuran, 1,4-dioxane, etc.; or mixtures thereof.

As the photopolymerization initiator, any compounds known to be usablein a photocurable resin composition may be used without significantlimitations, and specifically, a benzophenone-based compound, anacetophenone-based compound, a biimidazole-based compound, atriazine-based compound, an oxime-based compound, or mixtures of two ormore kinds thereof may be used.

The photopolymerization initiator may be used in the content of 1 to 100parts by weight, based on 100 parts by weigh of the photopolymerizablecompound. If the content of the photopolymerization initiator is toosmall, materials that remain without being cured in the step ofphotocuring of the photocurable coating composition may be generated. Ifthe content of the photopolymerization initiator is too large, unreactedinitiators may remain as impurities or a crosslinking density may belowered, and thus the mechanical properties of the prepared film may bedeteriorated or reflectance may significantly increase.

Meanwhile, the photocurable coating composition may further include anorganic solvent.

Non-limiting examples of the organic solvent may include, for example,ketones, alcohols, acetates, ethers, and mixtures of two or more kindsthereof.

Specific examples of the organic solvent may include ketones such asmethyl ethyl ketone, methyl isobutyl ketone, acetylacetone, isobutylketone, etc.; alcohols such as methanol, ethanol, diacetone alcohol,n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, etc.; acetatessuch as ethyl acetate, i-propyl acetate, polyethylene glycolmonomethylether acetate, etc.; ethers such as tetrahydrofuran orpropylene glycol monomethylether, etc.; and mixtures of two or morekinds thereof.

The organic solvent may be added when mixing the components included inthe photocurable coating composition, or each component may be added tothe photocurable coating composition while being dispersed in or mixedin the organic solvent. If the content of the organic solvent in thephotocurable coating composition is too small, flowability of thephotocurable coating composition may be deteriorated, and thus defectssuch as stripes, etc. may be generated in the finally prepared film.Further, if the organic solvent is excessively added, solid content maydecrease, and thus coating and film formation may not be sufficientlyachieved, thus deteriorating the physical properties or surface propertyof the film, and generating defects in the process of drying and curing.Thus, the photocurable coating composition may include an organicsolvent such that the total solid concentration of the includedcomponents may become 1 to 50% by weight, or 2 to 20% by weight.

The hard coating layer may have a thickness of 0.1 μm to 100 μm.

The anti-reflective film may further include a substrate bonded to theother side of the hard coating layer. Specific kinds or thicknesses ofthe substrate are not particularly limited, and substrates known to beused in the preparation of low refractive layers or anti-reflectivefilms may be used without particular limitations.

Meanwhile, an anti-reflective film of the above embodiment can beprovided through the preparation method of an anti-reflective film,including the steps of: applying a resin composition for forming a lowrefractive index layer including a photopolymerizable compound or a(co)polymer thereof, a fluorine-containing compound including aphotoreactive functional group, a photoinitiator, hollow inorganicnanoparticles and solid inorganic nanoparticles onto a hard coatinglayer, and drying it at a temperature of 35° C. to 100° C.; andphotocuring the dried product of the resin composition.

The low refractive index layer can be formed by applying a resincomposition for forming a low refractive index layer including aphotopolymerizable compound or a (co)polymer thereof, afluorine-containing compound including a photoreactive functional group,a photoinitiator, hollow inorganic nanoparticles, and solid inorganicnanoparticles on a hard coating layer, and drying it at a temperature of35° C. to 100° C., or 40° C. to 80° C.

If the temperature for drying the resin composition for forming a lowrefractive index layer applied on the hard coating layer is less than35° C., the formed low refractive index layer may be significantlydeteriorated in anti-fouling property. Further, if the temperature fordrying the resin composition for forming a low refractive index layerapplied on the hard coating layer is greater than 100° C., in thepreparation process of the low refractive index layer, phase separationbetween the hollow inorganic nanoparticles and the solid inorganicnanoparticles may not sufficiently occur and they may unevenlydistribute, thus deteriorating scratch resistance and anti-pollutionproperties of the low refractive layer and also significantly increasingin the reflectivity.

In the process of drying the resin composition for forming the lowrefractive index layer applied on the hard coating layer, by adjustingthe density difference between the solid inorganic nanoparticles and thehollow inorganic nanoparticles together with the drying temperature, thelow refractive layer having the above-mentioned characteristics can beformed. The solid inorganic nanoparticles may have a density which is0.50 g/cm³ or more higher than that of the hollow inorganicnanoparticles. Due to such a density difference, the solid inorganicnanoparticles in the low refractive index layer formed on the hardcoating layer may be located on the side closer to the hard coatinglayer.

Meanwhile, the step of drying the resin composition for forming a lowrefractive layer applied onto the hard coating layer at a temperature of35° C. to 100° C. may be performed for 10 seconds to 5 minutes, or 30seconds to 4 minutes.

If the drying time is too short, phase separation between the solidinorganic nanoparticles and the hollow inorganic nanoparticles may notsufficiently occur. To the contrary, if the drying time is too long, theformed low refractive index layer may erode the hard coating layer.

Meanwhile, as the hard coating layer, commonly known hard coating layersmay be used without particular limitations.

One example of the hard coating layer may include a hard coating layerincluding a binder resin including a photocurable resin, and organic orinorganic fine particles dispersed in the binder resin.

The photocurable resin included in the hard coating layer may be apolymer of photocurable compounds capable of inducing a polymerizationreaction if light such as UV, etc. is irradiated, as is commonly knownin the art. Specifically, the photocurable resin may include one or moreselected from the group consisting of: reactive acrylate oligomers suchas a urethane acrylate oligomer, an epoxide acrylate oligomer, apolyester acrylate, and a polyether acrylate; and multifunctionalacrylate monomers such as dipentaerythritol hexaacrylate,dipentaerythritol hydroxy pentaacrylate, pentaerythritol tetraacrylate,pentaerythritol triacrylate, trimethylene propyl triacrylate,propoxylated glycerol triacrylate, trimethylpropane ethoxy triacrylate,1,6-hexanediol acrylate, propoxylated glycerol triacrylate, tripropyleneglycol diacrylate, and ethylene glycol diacrylate.

Although the particle diameter of the organic or inorganic fineparticles is not specifically limited, for example, the organic fineparticles may have a particle diameter of 1 μm to 10 μm, and theinorganic fine particles may have a particle diameter of 1 nm to 500 nm,or 1 nm to 300 nm. The particle diameter of the organic or inorganicfine particles may be defined as a volume average particle diameter.

Further, although specific examples of the organic or inorganic fineparticles included in the hard coating layer are not particularlylimited, for example, the organic or inorganic fine particles may beorganic fine particles selected from the group consisting of acryl-basedresin particles, styrene-based resin particles, epoxide resin particles,and nylon resin particles, or inorganic fine particles selected from thegroup consisting of silicon oxide, titanium dioxide, indium oxide, tinoxide, zirconium oxide, and zinc oxide.

The binder resin of the hard coating layer may further include a highmolecular weight (co)polymer with a weight average molecular weight of10,000 or more.

The high molecular weight (co)polymer may be one or more selected fromthe group consisting of a cellulose-based polymer, an acryl-basedpolymer, a styrene-based polymer, an epoxide-based polymer, anylon-based polymer, a urethane-based polymer, and a polyolefin-basedpolymer.

Meanwhile, another example of the hard coating layer may include a hardcoating layer including a binder resin of a photocurable resin; and anantistatic agent dispersed in the binder resin.

The photocurable resin included in the hard coating layer may be apolymer of photocurable compounds capable of inducing a polymerizationreaction by the irradiation of light such as UV, etc., that is commonlyknown in the art. However, preferably, the photocurable compound may bemultifunctional (meth)acrylate-based monomers or oligomers, wherein itis advantageous in terms of securing of the properties of the hardcoating layer for the number of (meth)acrylate-based functional groupsto be 2 to 10, preferably 2 to 8, and more preferably 2 to 7. Morepreferably, the photocurable compound may be one or more selected fromthe group consisting of pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, dipentaerythritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate,dipentaerythritol hepta(meth)acrylate, tripentaerythritolhepta(meth)acrylate, tolylene diisocyanate, xylene diisocyanate,hexamethylene diisocyanate, trimethylol propane tri(meth)acrylate, andtrimethylol propane polyethoxy tri(meth)acrylate.

The antistatic agent may be: a quaternary ammonium salt compound;pyridinium salt; a cationic compound having 1 to 3 amino groups; ananionic compound such as a sulfonic acid base, a sulfuric ester base, aphosphoric ester base, a phosphonic acid base, etc.; an amphotericcompound such as an amino acid-based or amino sulfuric ester-basedcompound, etc.; a non-ionic compound such as an imino alcohol-basedcompound, a glycerin-based compound, a polyethylene glycol-basedcompound, etc.; an organometal compound such as a metal alkoxidecompound containing tin or titanium, etc.; a metal chelate compound suchas an acetylacetonate salt of the organometal compound, etc.; reactantsor polymerized products of two or more kinds of these compounds; ormixtures of two or more kinds of these compounds. Here, the quaternaryammonium salt compound may be a compound having one or more quaternaryammonium salt groups in the molecule, and a low molecular type or a highmolecular type may be used without limitations.

Further, as the antistatic agent, a conductive polymer and metal oxidefine particles may also be used. The conductive polymer may include anaromatic conjugated poly(paraphenylene), a heterocyclic conjugatedpolypyrrole, a polythiophene, an aliphatic conjugated polyacetylene, aheteroatom-containing conjugated polyaniline, a mixed conjugatedpoly(phenylene vinylene), a multi-chain type of conjugated compoundwhich is a conjugated compound having multiple conjugated chains in themolecule, a conductive complex in which a conjugated polymer chain isgrafted on or block copolymerized with a saturated polymer, etc.Further, the metal oxide fine particles may include zinc oxide, antimonyoxide, tin oxide, cerium oxide, indium tin oxide, indium oxide, aluminumoxide, antimony-doped tin oxide, aluminum-doped zinc oxide, etc.

The hard coating layer including a binder resin of a photocurable resin,and an antistatic agent dispersed in the binder resin, may furtherinclude one or more compounds selected from the group consisting of analkoxy silane-based oligomer and a metal alkoxide-based oligomer.

Although the alkoxy silane-based compound may be one commonly used inthe art, preferably, it may include one or more compounds selected formthe group consisting of tetramethoxysilane, tetraethoxysilane,tetraisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane,methacryloxypropyltrimethoxysilane, glycidoxy propyl trimethoxy silane,and glycidoxypropyltriethoxysilane.

Further, the metal alkoxide-based oligomer may be prepared by a sol-gelreaction of a composition including a metal alkoxide-based compound andwater. The sol-gel reaction may be conducted by a similar method to theabove-explained preparation method of the alkoxy silane-based oligomer.

However, since the metal alkoxide-based compound may rapidly react withwater, the sol-gel reaction may be performed by diluting the metalalkoxide-based compound in an organic solvent, and then, slowly drippingwater thereto. At this time, considering the reaction efficiency, it ispreferable that the mole ratio of the metal alkoxide-based compound towater (based on metal ions) is adjusted within a range of 3 to 170.

Here, the metal alkoxide-based compound may be one or more compoundsselected from the group consisting of titanium tetra-isopropoxide,zirconium isopropoxide, and aluminum isopropoxide.

According to another embodiment of the present disclosure, a polarizingplate including the anti-reflective film can be provided.

The polarizing plate may include a polarizer and an anti-reflective filmformed on at least one surface of the polarizer.

The material and preparation method of the polarizer are notparticularly limited, and the material and preparation method commonlyknown in the art can be used. For example, the polarizer may be apolyvinyl alcohol-based polarizer.

The polarizer and the anti-reflective film can be laminated by anadhesive such as an aqueous adhesive or a non-aqueous adhesive.

According to another embodiment of the present disclosure, a displaydevice including the above-mentioned anti-reflective film can beprovided.

A specific example of the display apparatus is not limited, and forexample, it may be a device such as a liquid crystal display device, aplasma display device, or an organic light emitting diode displaydevice, and a flexible display device.

In the display device, the anti-reflective film may be provided on theoutermost surface of an observer side or a backlight side of the displaypanel.

In the display device including the anti-reflective film, theanti-reflective film may be located on one surface of the polarizingplate relatively far from the backlight unit, among the pair ofpolarizing plates.

The display device may include a display panel, a polarizer provided onat least one surface of the panel, and an anti-reflective film providedon the opposite surface making contact the panel of the polarizer.

According to yet another embodiment of the present disclosure, anorganic light emitting diode display device including theanti-reflective film can be provided.

Generally, the organic light emitting diode display device has highresolution and high color reproduction capability. In the case of ananti-reflective film having high color values, for examples, acharacteristic that the absolute value of b* in the CIE Lab color spaceis greater than 4, the color reproduction capability of the organiclight emitting diode display device may be deteriorated.

On the contrary, the anti-reflective film of the one embodiment canrealize high light transmittance and low reflectance, have a colorlessand transparent property because the absolute value of b* in the CIE Labcolor space has a low color value of 4 or less, and thus can realize theeffect of maintaining or increasing the color reproduction capability ofthe organic light emitting diode display device.

Advantageous Effects

According to the present disclosure, an anti-reflective film that cansimultaneously realize high scratch resistance and anti-foulingproperties while having high light transmittance, and that has colorlessand transparent properties while realizing low reflectance, and apolarizing plate, a display device and an organic light emitting diodedisplay device including the same can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the reflectance pattern of the anti-reflective film ofExample 1.

FIG. 2 shows the reflectance pattern of the anti-reflective film ofExample 2.

FIG. 3 shows the reflectance pattern of the anti-reflective film ofExample 3.

FIG. 4 shows the reflectance pattern of the anti-reflective film ofExample 4.

FIG. 5 shows the reflectance pattern of the anti-reflective film ofExample 5.

FIG. 6 shows the reflectance pattern of the anti-reflective film ofExample 6.

FIG. 7 shows the reflectance pattern of the anti-reflective film ofComparative Example 1.

FIG. 8 shows the reflectance pattern of the anti-reflective film ofComparative Example 2.

FIG. 9 shows the reflectance pattern of the anti-reflective film ofComparative Example 3.

FIG. 10 shows the reflectance pattern of the anti-reflection film ofComparative Example 4.

Hereinafter, the present disclosure will be described in more detail inthe following examples. However, these examples are given forillustrative purposes only and the content of the present disclosure isnot intended to be limited to or by the examples in any way.

PREPARATION EXAMPLES 1 TO 2: PREPARATION OF HARD COATING LAYERPreparation Example 1: Preparation of Hard Coating Layer HD1

Solid components of 75 g of trimethylolpropane trimethacrylate (TMPTA),2 g of silica fine particles having an average particle diameter of 20nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane),0.05 g of fluorine-based acrylate (RS-537, DIC) and 1.13 g ofphotoinitiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethylketone) solvent so that a solid content concentration was 40 wt. %,thereby preparing a hard coating composition.

The diluted hard coating solution was coated onto a triacetyl cellulosefilm using a #10 mayer bar, dried and photocured under the conditions ofTable 1 below to prepare a hard coating film having a thickness of 5 μm.

The wind speed applied during drying of the hard coating layer in eachof the following Examples and Comparative Examples is shown in Table 2below.

Preparation Example 2: Preparation of Hard Coating Layer HD2

Solid components of 75 g of trimethylolpropane trimethacrylate (TMPTA),2 g of silica fine particles having an average particle diameter of 20nm (surface treatment: 3-methacryloyloxypropylmethyldimethoxysilane),0.5 g of fluorine-based acrylate (RS-537, DIC) and 1.13 g ofphotoinitiator (Irgacure 184, Ciba) were diluted in a MEK (methyl ethylketone) solvent so that the solid content concentration was 40 wt. %,thereby preparing a hard coating composition.

The diluted hard coating solution was coated onto a triacetyl cellulosefilm using a #10 mayer bar, dried and photocured under the conditions ofTable 1 below to prepare a hard coating film having a thickness of 5 μm.

The wind speed applied during drying of the hard coating layer in eachof the following Examples and Comparative Examples is shown in Table 2below.

TABLE 1 Nitrogen purging UV intensity during photocuring [mJ/cm²]Preparation Example 1 ◯  25 mJ/cm² Preparation Example 2 ◯ 254 mJ/cm²

PREPARATION EXAMPLES 3 TO 6: PREPARATION OF LOW REFRACTIVE INDEX LAYERCOATING COMPOSITION Preparation Example 3: Preparation of PhotocurableCoating Composition for Preparing Low Refractive Index Layer

Based on 100 parts by weight of trimethylolpropane trimethacrylate(TMPTA), 281 parts by weight of hollow silica nanoparticles (diameter:about 50 to 60 nm, density: 1.96 g/cm³, manufactured by JSC Catalyst andChemicals), 63 parts by weight of solid silica nanoparticles (diameter:about 12 nm, density: 2.65 g/cm³, Nissan Chemical), 131 parts by weightof a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 19parts by weight of a second fluorine-containing compound (RS-537, DIC),and 31 parts by weight of an initiator (Irgacure 127, Ciba) were dilutedin a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol(DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solidcontent concentration was 3 wt. %.

Preparation Example 4: Preparation of Photocurable Coating Compositionfor Preparing Low Refractive Index Layer

Based on 100 parts by weight of trimethylolpropane trimethacrylate(TMPTA), 200 parts by weight of hollow silica nanoparticles (diameter:about 50 to 60 nm, density: 1.96 g/cm³, manufactured by JSC Catalyst andChemicals), 48 parts by weight of solid silica nanoparticles (diameter:about 12 nm, density: 2.65 g/cm³, Nissan Chemical), 111 parts by weightof a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 15parts by weight of a second fluorine-containing compound (RS-537, DIC),and 21 parts by weight of an initiator (Irgacure 127, Ciba) were dilutedin a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol(DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solidcontent concentration was 3 wt. %.

Preparation Example 5: Preparation of Photocurable Coating Compositionfor Preparing Low Refractive Index Layer

Based on 100 parts by weight of trimethylolpropane trimethacrylate(TMPTA), 300 parts by weight of hollow silica nanoparticles (diameter:about 60 to 70 nm, density: 1.79 g/cm³, manufactured by JSC Catalyst andChemicals), 85 parts by weight of solid silica nanoparticles (diameter:about 12 nm, density: 2.65 g/cm³, Nissan Chemical), 150 parts by weightof a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 33parts by weight of a second fluorine-containing compound (RS-537, DIC),and 35 parts by weight of an initiator (Irgacure 127, Ciba) were dilutedin a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol(DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solidcontent concentration was 3 wt. %.

Preparation Example 6: Preparation of Photocurable Coating Compositionfor Preparing Low Refractive Index Layer

Based on 100 parts by weight of trimethylolpropane trimethacrylate(TMPTA), 248 parts by weight of hollow silica nanoparticles (diameter:about 60 to 60 nm, density: 1.96 g/cm³, manufactured by JSC Catalyst andChemicals), 68 parts by weight of solid silica nanoparticles (diameter:about 12 nm, density: 2.65 g/cm³, Nissan Chemical), 120 parts by weightof a first fluorine-containing compound (X-71-1203M, Shin-Etsu), 33parts by weight of a second fluorine-containing compound (RS-537, DIC),and 30 parts by weight of an initiator (Irgacure 127, Ciba) were dilutedin a mixed solvent of methyl isobutyl ketone (MIBK):diacetone alcohol(DAA):isopropyl alcohol in a weight ratio of 3:3:4 so that the solidcontent concentration was 3 wt. %.

EXAMPLE AND COMPARATIVE EXAMPLE: PREPARATION OF LOW REFRACTIVE INDEXLAYER AND ANTI-REFRACTIVE FILM

The photocurable coating composition obtained above was coated onto ahard coating layer of Preparation Examples 1 to 2 at a thickness of 120nm using a #4 mayer bar, dried and cured under the conditions of Table 2below.

At the time of curing, it proceeded under nitrogen purging, and thedrying was performed at a temperature was 90° C. for 1 minute.

TABLE 2 Hard coating layer Low refractive Hard coating drying wind speed(m/s) index layer Example 1 Preparation Example 1 0.5 PreparationExample 3 Example 2 Preparation Example 1 0.5 Preparation Example 4Example 3 Preparation Example 1 1.0 Preparation Example 4 Example 4Preparation Example 1 0.5 Preparation Example 5 Example 5 PreparationExample 1 0.5 Preparation Example 6 Example 6 Preparation Example 1 1.0Preparation Example 6 Comparative Preparation Example 1 0.3 PreparationExample 6 Example 1 Comparative Preparation Example 2 0.3 PreparationExample 5 Example 2 Comparative Preparation Example 2 0.5 PreparationExample 5 Example 3 Comparative Preparation Example 2 0.7 PreparationExample 3 Example 4

EXPERIMENTAL EXAMPLE: MEASUREMENT OF PHYSICAL PROPERTIES OFANTI-REFLECTIVE FILM

The following experiments were performed for the anti-reflective filmsobtained in Examples and Comparative Examples.

1. Measurement of Surface Energy of Hard Coating Film

The surface energies of the hard coating layers of each of Examples andComparative Examples were measured by determining a contact angle of DIwater (Gebhardt) and diiodomethane (Owens) at 10 points using a contactangle measuring apparatus DSA-100 (Kruss), calculating the averagevalue, and then converting the average contact angle into the surfaceenergy. In the measurement of the surface energy, the contact angle wasconverted into the surface energy by using Dropshape Analysis softwareand applying the following Equation 2 of the OWRK (Owen, Wendt, Rable,Kaelble) method to the program.

γ_(L)(1+cos θ)=2√{square root over (γ_(S) ^(D)γ_(L) ^(D))}+2√{squareroot over (γ_(S) ^(P)γ_(L) ^(P))}  [Equation 2]

2. Measurement of Reflectance of Anti-Reflective Film and b* in CIE LabColor Space

For the anti-reflective films obtained in Examples and ComparativeExamples, the reflectance and b* at each wavelength in the visible lightregion (380 to 780 nm) were measured using a Solidspec 3700 (SHIMADZU)equipment. After scanning the specimen from 380 nm to 780 nm andmeasuring the reflectance at each wavelength, the average reflectanceand b* were derived using the UV-2401PC Color Analysis program.

3. Measurement of Anti-Fouling Property

Three straight lines were drawn with a red permanent marker on thesurface of the anti-reflective films obtained in Examples andComparative Examples. Then, the anti-fouling property was evaluatedthrough the number of erasing times when rubbing with a nonwoven cloth.

<Measurement Standard>

◯: Erase when rubbing 10 times or less

Δ: Erase when rubbing 11 to 20 times

X: Erase when rubbing 20 times or more

4. Measurement of Scratch Resistance

The surface of the anti-reflective films obtained in Examples andComparative Examples was rubbed back and forth 10 times with steel wool(#0000) under a load at a speed of 27 rpm. The scratch resistance wasobtained by measuring the maximum load at which a scratch of 1 cm orless observed with the naked eye was 1 or less.

5. Ellipsometry Measurement

For the anti-reflective films each obtained in Examples and ComparativeExamples, the polarization ellipticity was measured by an ellipsometrymethod.

Specifically, the ellipsometry was measured for the antireflection filmseach obtained in Examples and Comparative Examples at an incidence angleof 70° in a wavelength range of 380 nm to 1000 nm using a J. A. WoollamCo. M-2000 apparatus.

The measured ellipsometry data (ψ, λ) was fitted to a Cauchy model ofthe following Equation 1 for Layer 1 and Layer 2 of the lower refractiveindex layer using Complete EASE software.

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}1} \right\rbrack\end{matrix}$

in the above Equation 1, n(λ) is a refractive index at a wavelength λ, λis in a range of 300 nm to 1800 nm, and A, B, and C are Cauchyparameters.

In addition, for the mixed layer of the low refractive index layer, therefractive index and thickness were fitted to a diffuse layer model. MSEof The Cauchy model and the diffuse layer model was set to be 5 or less.

6. Measurement of Refractive Index

For the mixed particle layer included in the low refractive index layerobtained in Examples, the refractive indexes at wavelengths of 550 nmand 400 nm were calculated using a polarization ellipticity measured ata wavelength of 380 nm to 1,000 nm, a Cauchy model, and a diffuse layermodel.

TABLE 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Average reflectance (%) 0.9 1.35 1.42 0.6 1.1 1.2 b value in CIE Labcolor 3.3 2.9 1.2 1.5 2.5 2.1 space Surface energy of hard 35 35 35 3535 35 coating layer [mN/m] Position of the particle-mixed 32 45 40 31 5116 layer from the hard coating layer (nm) Thickness of the particle- 2.511.1 12.9 8.62 5.8 18.1 mixed layer (nm) Reflectance of anti-reflective0.8093 1.1233 1.3193 0.598 0.9895 1.121 film at a wavelength of 550 nmReflectance of anti-reflective 1.3768 2.5755 2.3928 1.299 1.7627 1.5946film at a wavelength of 400 nm Ratio of reflectance at 1.70 2.29 1.812.17 1.78 1.42 wavelength 400 nm to reflectance at wavelength 550 nmScratch resistance (g) 500 500 500 500 500 500 Anti-fouling ◯ ◯ ◯ ◯ ◯ ◯Phase separation ◯ ◯ ◯ ◯ ◯ ◯

TABLE 4 Comparative Comparative Comparative Comparative Example 1Example 2 Example 3 Example 4 Average reflectance (%) 0.92 0.7 0.75 0.84b value in CIE Lab color space 4.2 5.1 4.5 −7.73 Surface energy of hardcoating layer 33 32 33 34 [mN/m] Position of the particle-mixed layer 1110 65 13.4 from the hard coating layer (nm) Thickness of theparticle-mixed 22.12 25.98 31.58 1.31 layer (nm) Reflectance ofanti-reflective film 0.875 0.5877 0.6521 0.78 at a wavelength of 550 nmReflectance of anti-reflective film 2.3886 1.9539 1.9844 2.55 at awavelength of 400 nm Ratio of reflectance at wavelength 2.73 3.32 3.043.27 400 nm to reflectance at wavelength 550 nm Scratch resistance (g)150 50 200 100 Anti-fouling X X X X Phase separation X X X X

As shown in Table 3, it was confirmed that the anti-refractive films ofExamples, in which a particle-mixed layer containing both hollowinorganic nanoparticles and solid inorganic nanoparticles and having athickness of 1.5 nm to 22 nm exists in the low refractive index layer,realize a reflectance of 1.5% or less at a wavelength of 550 nm, andalso the ratio of the reflectance at a wavelength of 400 nm to thereflectance at a wavelength of 550 nm is 1.3 to 2.7.

Further, from the results of Table 3, it was confirmed that theanti-reflective films of Examples are phase-separated so as to dividethe regions in which the hollow inorganic nanoparticles and the solidinorganic nanoparticles are mainly distributed while including the mixedlayer in the low refractive index layer, and thus the anti-reflectivefilms realizes high scratch resistance and excellent anti-foulingproperties, and at the same time, the absolute value of b* in the CIELab color space has a low color value of 4 or less, which can havecolorless and transparent properties.

On the contrary, as shown in Table 4, in the anti-reflective films ofComparative Examples, it appears that regions where the hollow inorganicnanoparticles and the solid inorganic nanoparticles are mainlydistributed are divided, and thus not unevenly distributed (phaseseparated), confirming that scratch resistance or anti-foulingproperties are not sufficient.

In addition, from the results of Table 4, it appears that aparticle-mixed layer having a thickness of more than 22 nm exists in thelow refractive index layer of the anti-reflective films of ComparativeExamples, or the particle-mixed layer is located excessively close to ortoo far from the hard coating layer, and it was confirmed that in theanti-reflective films of these Comparative Examples, the ratio of thereflectance at a wavelength of 400 nm to the reflectance at a wavelengthof 550 nm exceeds 2.7, the films show a blue color and have an opacityor color property to a degree that is not suitable for application to apolarizing plate or a display device.

1. An anti-reflective film comprising: a hard coating layer; and a lowrefractive index layer, wherein a particle-mixed layer containing bothhollow inorganic nanoparticles and solid inorganic nanoparticles andhaving a thickness of 1.5 nm to 22 nm exists in the low refractive indexlayer, and wherein the anti-reflective film has a ratio of thereflectance at a wavelength of 400 nm to the reflectance at a wavelengthof 550 nm of 1.3 to 2.7.
 2. The anti-reflective film according to claim1, wherein the anti-reflective film has a reflectance of more than 0.5%and 1.5% or less at a wavelength of 550 nm.
 3. The anti-reflective filmaccording to claim 1, wherein the anti-reflective film has a reflectanceof 1.0% to 3.5% at a wavelength of 400 nm.
 4. The anti-reflective filmaccording to claim 1, wherein the particle-mixed layer has a thicknessof 2.0 nm to 20 nm.
 5. The anti-reflective film according to claim 1,wherein the thickness of the particle-mixed layer is determined byfitting a polarization ellipticity measured by an ellipsometry method toa diffusion layer model.
 6. The anti-reflective film according to claim1, wherein the low refractive index layer is formed on one surface ofthe hard coating layer, and the particle-mixed layer is located at adistance of 15 nm to 60 nm from the one surface of the hard coatinglayer.
 7. The anti-reflective film according to claim 1, wherein the lowrefractive index layer has a thickness of 20 nm to 240 nm.
 8. Theanti-reflective film according to claim 1, wherein the hard coatinglayer has a surface energy of more than 34 mN/m.
 9. The anti-reflectivefilm according to claim 1, wherein the low refractive index layer isformed on one surface of the hard coating layer, the low refractiveindex layer comprises hollow inorganic nanoparticles and solid inorganicnanoparticles dispersed in a binder resin, 50% by volume or more of theentire solid inorganic nanoparticles in the low refractive index layerexist between the one surface of the hard coating layer and theparticle-mixed layer.
 10. The anti-reflective film according to claim 6,wherein a region between the one surface of the hard coating layer andthe particle-mixed layer has a refractive index of 1.46 to 1.65 at awavelength of 550 nm.
 11. The anti-reflective film according to claim 9,wherein in the low refractive index layer, 50% by volume or more of theentire hollow inorganic nanoparticles exist in a region from theparticle-mixed layer to one surface of the low refractive index layeropposite from the hard coating layer.
 12. The anti-reflective filmaccording to claim 11, wherein the region from the particle-mixed layerto one surface of the low refractive index layer opposite from the hardcoating layer has a refractive index of 1.0 to 1.40 at a wavelength of550 nm.
 13. The anti-reflective film according to claim 1, wherein thesolid inorganic nanoparticles have a diameter of 0.5 to 100 nm, and thehollow inorganic nanoparticles have a diameter of 1 to 200 nm.
 14. Theanti-reflective film according to claim 1, wherein a difference indensity between the solid inorganic nanoparticles and the hollowinorganic nanoparticles is 0.50 g/cm³ to 3.00 g/cm³.
 15. Theanti-reflective film according to claim 1, wherein the low refractiveindex layer comprises a binder resin, and hollow inorganic nanoparticlesand solid inorganic nanoparticles dispersed in the binder resin, and thebinder resin included in the low refractive index layer comprises acrosslinked (co)polymer between a (co)polymer of a photopolymerizablecompound and a fluorine-containing compound including a photoreactivefunctional group.
 16. The anti-reflective film according to claim 1,wherein the hard coating layer comprises a binder resin including aphotocurable resin, and organic or inorganic fine particles dispersed inthe binder resin.
 17. A polarizing plate comprising the anti-reflectivefilm of claim 1 and a polarizer.
 18. A display device comprising theanti-reflective film of claim
 1. 19. An organic light emitting diodedisplay device comprising the anti-reflective film of claim 1.